The dark sector, composed of fields that are neutral under the standard model (SM) gauge group, can couple to SM through Higgs, hypercharge and neutrino portals, pull towards its scale by loop corrections. This instability, which is not possible prevent in known completions, such as supersymmetry, due sizable couplings SM, calls for alternative mechanisms neutralize sensitivities sector ultravi...

For a finitely generated discrete group Γ, the Γ-sectors of an orb-ifold Q are a disjoint union of orbifolds corresponding to homomorphisms from Γ into a groupoid presenting Q. Here, we show that the inertia orbifold and k-multi-sectors are special cases of the Γ-sectors, and that the Γ-sectors are orbifold covers of Leida's fixed-point sectors. In the case of a global quotient, we show that th...

The search for intersecting brane solutions in supergravity is a large and profitable industry. Recently, attention has focused on finding localized forms of known ‘delocalized’ solutions. However, in some cases, a localized version of the delocalized solution simply does not exist. Instead, localized separated branes necessarily delocalize as the separation is removed. This phenomenon is relat...